The use of a wiper die to solve the tube wrinkling problem discussed above is known in the prior art as exemplified by items 11, 43, 48 and 173 respectively in U.S. Pat. Nos. 878,604, 1,135,875, 1,261,191 and 3,456,482. Each of these prior art wiper dies involves the necessary complex underside surface generation to enable the forward portion of the wiper die to coact with the surface configuration of the forming die and yet extend forward sufficiently enough to provide as much sidewall support for the tube workpiece as possible prior to its reaching its tangency point with the forming die. When this forward portion of the wiper die, which is referred to as the feather-edge in the tube bending art, is worn or damaged and thereby presents a gap between such feather-edge and the point of tangency with the forming die where the tube bend or deflection forming begins, the wrinkling or gathering of the inner radius of the tube wall as described above has a tendency to begin, which in turn results in an unsmooth inner tube wall at or through the bend. To compensate for this gap due to wear and continue to attain high quality tube bends, the production process must be interrupted for an operator to replace, readjust and realign the mounting of another wiper die to the tube bending machine.